1. Field of the Invention
The invention relates to image processing and more particularly to a method and apparatus for the capture and digitizing of an electronically-scanned image.
2. Description of the Prior Art
In U.S. Pat. No. 4,196,450, which was granted to Armin Miller and Maxwell G. Maginness on Apr. 1, 1980, there is described a selective copying apparatus. In that apparatus a hand-held scanner is used by an operator to scan a selected portion of a document by placing the scanner at a desired line position and moving the scanner across the document. The scanned image is converted into digital data. The digital data is in a form which can be processed by a microprocessor and manipulated by input/output devices such as a CRT display and a printer. It is, however, necessary that the hand-held scanner be in contact with the object being scanned in order that the mechanical scan operation can be synchronized with the electronic scan of a photodiode array within the scanner.
To provide for noncontact image scanning, the Datacopy Series 300 high-resolution digitizing cameras were developed by Datacopy Corporation of Mountain View, Calif. A Series 300 camera may be used as a digitizer to capture images of alphanumerics, graphics, and two-dimensional or three-dimensional objects. The Series 300 camera focuses the image of an object to be scanned on the image plane of the camera. The camera's optical system is held stationary while a self-scanning linear array, comprised of a row of light-sensitive devices, is moved a measured distance in the image plane. The linear array is continuously clocked as it is moved along the image plane. The resulting video signal output is a train of pulses, each proportional in magnitude to the light intensity falling on the corresponding light-sensitive device at the time it is sampled. The output of the array is utilized at sequential position intervals of the array as the array is moved in the image plane, to thus provide a video output line scan in two dimensions of the image focused at the image focal plane.
In the Series 300 camera, the scanning and digitizing functions are performed automatically. That is, the camera electronics control the mechanical movement of the array and synchronizes the electrical scanning of the light-sensitive devices. In order to provide for a wider range of system applications, it is desirable to have a digitizing camera in which the mechanical and electrical scanning functions can be controlled by commands from a host computer; for example, through a peripheral interface adapter (PIA) available from semiconductor manufacturers. These interfaces are typically parallel interface devices available on microcomputers and microcomputer development systems. The PIA is thus used in conjunction with a microprocessor for commanding the camera operations and requesting status from the camera, just as if the camera were a conventional input/output device such as a a disk, drum, tape drive, etc.